6 Possible Reasons You're Experiencing Sudden, Rapid Weight Loss

With all the stats you hear about obesity in America, you might think of weight loss as an inherently good thing. But when weight loss is rapid and unintended, it can signal a worrisome underlying condition.

First, what’s considered "rapid" weight loss?

“Although we do not often have a widely accepted standardized definition of rapid weight loss, we do consider significant, unintentional weight loss to be 5% or greater weight reduction over six to 12 months,” says Greg Jun, MD, an internal medicine physician with Northwestern Medicine McHenry Hospital.

While typical weight loss is due to a change in lifestyle habits, decreased caloric intake, or an increase in physical activity, unexpected weight loss due to none of the above can throw up some red flags.

“Weight loss that includes other red flag symptoms like fatigue, fevers, change in bowel habits or pain should definitely prompt a phone call to your primary care provider,” Jun says.

Unexplained weight loss can be from a multitude of underlying conditions. Here are 6 possible causes of sudden, rapid weight loss.

1) You have a gut disease.

“Diseases of the bowel will generally include some sort of additional symptoms, like decreased appetite, nausea or vomiting, abdominal bloating/pain or change in bowel habit,” says Cory Fisher, DO, family medicine physician at the Cleveland Clinic.

Some examples include inflammatory bowel disease (Crohn’s disease and ulcerative colitis), celiac disease, and chronic liver disease. Your primary care doctor may refer you to a gastroenterologist for diagnosis, which usually requires imaging studies or endoscopy.

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2) You have hyperthyroidism.

This is due to an over-active thyroid.

“Weight loss is primarily due to increased metabolic rate and secondarily due to increased gut mobility, with resulting malabsorption,” says Jun. You may also experience symptoms like fatigue, sleep changes, irritability, and difficulty regulating your body temperature.

“Once hyperthyroidism is diagnosed, there are multiple approaches to treating the condition that a person can discuss with their primary care provider and possibly an endocrinology specialist,” says Jun. “Treatment may involve medications, radioactive iodine or surgery.”

3) You have a parasite.

This is creepy, but it happens. Two of the most common intestinal parasites are giardia and crypto (Cryptosporidium).

“Weight loss is usually due to malabsorption and malnutrition because the parasite is actually taking in the nutrients the person is eating,” says Jun. “Use good personal hygiene, such as washing your hands often. And when you travel, make sure to drink clean water and make sure food is handled properly at restaurants.”

Treatment will be specific to the kind of parasite that is identified, which will most likely take some testing.

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4) You have depression.

Early identification and awareness is key when depression and other psychological conditions (like anxiety) may be causing weight loss.

“Depression can often lead to decreased appetite,” says Jun. “Decreased caloric intake can lead to weight loss. There may also be an accompanying eating disorder, so a person should be evaluated for that as well.”

Treatment often involves a multidisciplinary approach such as medications, dietary and lifestyle modification education, counseling and behavioral modification, says Jun.

5) You have diabetes.

“If a person with diabetes has insufficient insulin, the body may not be able to get glucose (sugar) from the blood into the cells to use as energy, and this may lead to the body breaking down fat and muscle for energy, possibly resulting in weight loss,” says Jun.

Other symptoms of diabetes include excessive thirst or urination, sweats, fatigue, and numbness.

Your primary care doctor can do blood glucose testing to determine if you have diabetes, especially if you have a family history of diabetes.

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6) You have cancer.

Yes, the ‘C’ word could be an indicator of these symptoms.

“Cancer can cause weight loss, and not certain cancers, but cancer of many types,” Fisher says.

According to the American Cancer Society, unexplained weight loss of 10 pounds or more is one of the most common symptoms of with cancers of the pancreas, stomach, esophagus, or lung.

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